A problem with the glymphatic system could mean that amyloid is not being removed correctly

The brain has a waste removal process that could one day be used to better treat problems like Alzheimer's disease.

Researchers from the University of Rochester Medical Center (URMC) -- led by Maiken Nedergaard, M.D., D.M.Sc., co-director of the URMC Center for Translational Neuromedicine -- detailed a recently discovered waste removal system in the brain, and believes it could hold the key to understanding and treating diseases like Alzheimer's.

It's been long understood that the lymphatic system, which is a circulatory network of vessels and organs, is responsible for waste removal throughout the body. However, it doesn't perform this task in the brain. Last August, URMC researchers discovered the glymphatic system, which filled in the missing piece as the brain's own "garbage truck."

The glymphatic system works like this: the brain is surrounded by the arachnoid membrane, which is covered in cerebral spinal fluid (CSF). CSF uses pathways that lead into the brain with the support of glia cells. These are the same pathways that arteries use to carry blood, creating a parallel system where CSF is carried through on an outer ring and blood is carried through the inner ring.

CSF is rushed through the brain quickly, carrying waste such as excess proteins along with it as it sweeps through. This waste is then sent off into a similar system that parallels veins, and it travels down the spine until it is transferred to the lymphatic system. From there, it goes to the liver and is broken down.

Researchers didn't discover this system until just last year because it cannot be seen in brain tissue samples. Instead, the team had to use imaging technology called two-photon microscopy. This allowed scientists to look within the brains of mice, thus discovering the glymphatic system.

This study could help researchers find new ways to treat disorders like Alzheimer's disease because the disease is marked by the accumulation of the protein beta amyloid in the brain. A problem with the glymphatic system could mean that amyloid is not being removed correctly.